Time relentlessly destroys youth and beauty, turning the initial vitality of nativity into age and decay; only the speaker's verse offers hope of immortalizing the young man against time's cruel hand.
The opening quatrain's wave imagery is not decorative but structurally brilliant. Each wave moves toward shore only to be replaced by the next; similarly, each moment of life rushes toward death only to be followed by the next moment. The metaphor binds personal time to cosmic time. Yet waves are also cyclical—they return, renew. Shakespeare complicates this: the wave image captures both the inevitability of forward motion and the terrifying repetition of loss. Youth cannot return; the wave breaks and dissipates on the shore. This merging of natural beauty (waves) with temporal horror (erasure) sets the sonnet's emotional tone.
From line 8 onward, Time becomes a predatory force. It is not neutral or natural but actively malicious: it 'transfixes' (impales), 'delves' (carves), and 'feeds' on beauty. The image of Time as a harvester with a scythe makes death literal—a reaping. Yet the most disturbing image is temporal: Time 'gave' youth as a gift and now 'confounds' (destroys) that same gift. The young man's beauty is Time's own creation, now consumed by its creator. This inversion—where the destroyer created what it destroys—reveals time as a fundamentally cannibalistic force. The couplet's assertion that verse can resist this cannibalism is deliberately fragile against such cosmic horror.
Like watching someone age in real time through social media, or realizing that no matter how hard you work to stay young and beautiful, time is always winning. The sonnet captures the fear that beauty and health are temporary possessions time will steal.